Characteristics of the gain and signal-to-noise ratio of a distributed erbium-doped fiber amplifier

The effects of stimulated Raman scattering (SRS) on the gain and signal-to-noise ratio (SNR) of the DEDFA with 100-km fiber length and with bidirectional pumps are numerically studied. It is found that the gain and SNR are significantly enhanced by the SRS with practical parameters. For 1.55- mu m signal and 10- mu W initial signal power, there are 8.8-dB gain enhancement and 3.3-dB SNR enhancement for 1.48- mu m pump wavelength and 75-mW initial pump power. The characteristics of the gain and SNR enhancements due to SRS are studied for different signal wavelength, signal powers, pump wavelengths, pump powers, and effective fiber cross sections. The results show that the gain and SNR are decreased by SRS only for the unpractical high pump power and/or small effective fiber cross section.<
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